Status of the optical payload and processor development of ESAs - - PowerPoint PPT Presentation

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Status of the optical payload and processor development of ESAs - - PowerPoint PPT Presentation

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Status of the optical payload and processor development of ESAs Sentinel 3 B. Berruti, J. Frerick, C. Mavrocordatos, J. Nieke , H. Rebhan, J. Stroede and the S3 Team, European Space Agency, ESTEC, Keplerlaan 1, 2200AG Noordwijk ZH, The

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26-Sep-2008

Status of the optical payload and processor development of ESA’s Sentinel 3

  • B. Berruti, J. Frerick, C. Mavrocordatos, J. Nieke, H. Rebhan, J. Stroede

and the S3 Team, European Space Agency, ESTEC, Keplerlaan 1, 2200AG Noordwijk ZH, The Netherlands

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26-Sep-2008

Outline

  • Programmatics
  • Satellite / Orbit
  • Optical Payload
  • Key Processors
  • Conclusion
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26-Sep-2008

3

Definition of 5 series of satellite missions:

– Sentinel 1: C-band SAR (possible 2 satellite constellation) – Sentinel 2: Super-spectral Imager at 10-30 m resolution

– Sentinel 3: Altimeter plus multi-spectral Vis/IR imager (OC & SST)

– Sentinel 4: Atmosphere Monitoring from geostationary orbits – Sentinel 5: Atmosphere Monitoring from low-earth orbits

S1 S2 S3 S4 S5

Marine & Coastal Environment * * * Land Cover state & changes * * * Global Change Issues * * * * *

  • Atmos. Pollution Management

* * * Risk Management * * * Forest Monitoring * * * Food Security * * * * * Marine Security * * Humanitarian Aid * * *

ESA GMES Space Segment

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Sentinel- 3 is designed to become an operational mission in low earth

  • rbit.

Sentinel-3 will provide consistent, long-term collection of remotely sensed Marine and Land data to support operational services.

Mission Overview

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26-Sep-2008

Marine Services

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Land Services

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Sentinel-3 implements three core P/L systems in continuity of existing

  • nes, delivering:
  • 1. Sea and land colour data, at least at the level of quality of the Medium

Resolution Imaging Spectrometer (MERIS) instrument,

  • 2. Sea and Land surface temperature, at least at the level of quality (ε < 0.3K)
  • f the Advanced Along-Track Scanning Radiometer (AATSR) instrument,
  • 3. Sea surface topography data, at least at the level of quality of the Radar

Altimeter (RA) system. In addition, the foreseen optical payload will allow to a certain degree

  • data continuity of the Vegetation instrument (on SPOT4/5),
  • enhanced fire monitoring capabilities.

Operational aspects:

  • Global ocean coverage in 1 to 3 days (taking into account sun-glint), and

co-registration of Color and Temperature measurements

  • NRT data delivery (< 3 hours) for fundamental products

Mission Overview

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Main satellite characteristics

  • 1198 kg maximal mass
  • Volume in 3.89 m x 2.202 m x 2.207 m
  • Average power consumption of 1100 W
  • 7.5 years lifetime (fuel for 5 add. years)
  • Large cold face for optical instruments
  • thermal control
  • Modular accommodation for a simplified
  • management of industrial interfaces
  • Launch second half 2012

Observation Data Management

  • 200 Gb of observation data per orbit
  • Space to ground data rate of 450 Mb/s
  • 1 contact per orbit
  • 3h timeliness

Orbit characteristics

  • Average altitude ~815 km
  • LTDN between 10 – 10:30
  • Near-Polar frozen Sun-Synchronous
  • (98.6 deg. inclination)
  • 27 days exact repeat cycle
  • 4 day global coverage (optical
  • mission) with 1 Satellite (less than
  • 2 days with two Satellites)

Orbit and S/C

S band antenna SRAL antenna X band antenna LRR MWR SRAL antenna X band antenna SLSTR OLCI LRR DORIS MWR

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Industrial Team

Selex Galileo SLSTR related ITTs:

FPA (Selex Galileo)

  • IR Detectors
  • Vis Detectors
  • Cryo Cooler
  • CPE

OME (Jena Optronik)

  • Structure
  • Black bodies
  • Visible Calibration Unit
  • Thermal Hardware
  • Telescope optics
  • Scanner Mechanisms
  • Flip mechanism
  • OME/EGSE

…

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26-Sep-2008

Data Acquisition Geometry Instrument operations are repetitive according to the satellite position

  • SLSTR incl. nadir & backward view
  • OLCI FOV optimised to avoid sun glint
  • SLSTR & OLCI will be available as L1C co-registered product
  • SLSTR (IR channels) and TOPO are always acquiring data
  • SRAL modes are fixed over specific geographical zones
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Coverage & Timeliness

  • Coverage:

Ocean surface: < 4 days (with Sun-glint, without clouds) Land surface: < 2 days (without Sun-glint and clouds)

  • Timeliness:

Level 1: NRT 3 hours product, assuming 1 hour for ground processing and 2 hours for satellite acquisition and downlink

OLCI mean revisit time map (14+7/27 orbit), with 1 satellite. 1 S/C 2 S/C

  • Max. of Longitude

Averaged Maximum Rev. Time Sea 4.0 2.0 Land 3.0 1.0

  • Max. of Longitude

Averaged Mean Rev. Time Sea 3.8 1.9 Land 1.4 0.8 Coverage performance (in days) of the OLCI payload on sea and land with 1 and 2 spacecrafts:

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Ocean & Land Color Instrument (OLCI)

VIS-NIR programmable imaging spectrometer: – 5 cameras in fan-shaped form, –

  • verall instrument FoV is 68.5 degrees, i.e., ~1300km

– instrument assembly tilted by about 12 deg across-track away from Sun avoiding sun-glint effects.

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OLCI Technical: Basic set-up:

5 fan-arranged Camera Optical Sub Assemblies (COSA), 5 Focal Plane Assemblies (FPA), 1 Scrambling Window Assembly (SWA), 5 Video Acquisition Modules (VAM), 1 OLCI Electronic Unit (OEU) managing all the instrument functions, 1 calibration assembly allowing a radiometric and spectral calibration. OLCI Optical layout

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Spectro-radiometric performance req.: Absolute radiometric accuracy < 2% Stability (during day time part of the orbit) < 0.1% Spectral misregistration < 0.0014 μm Inter-channel spatial co-registration < 0.4 FR SSD (400 - 900 nm) Inter-channel radiometric accuracy < 1% Out-of-band signal < 1% Polarization sensitivity < 0.01 Geometric performance req.: – FOV: 68.4º – Sampling Distance (in km): Open Ocean 1.2 1.2 RR Coastal Zone 0.3 0.3 FR Land 0.3 0.3 FR – Distortion < 1.4 % – MTF > 0.28 (at Nyquist) OLCI Performance

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additional bands still subject to change for better app/s, SNR/s and data-rates.

Band # λ center Width Lref Lsat radiance SNR nm nm W/(m².sr.µm) Lsat/Lmax W/(m².sr.µm) [-]

O1 400 15 62.95 0.8 413.5 2188 O2 412.5 10 74.14 1 501.3 2061 O3 442.5 10 65.61 0.8 466.1 1811 O4 490 10 51.21 0.8 483.3 1541 O5 510 10 44.39 0.8 449.6 1488 O6 560 10 31.49 1 524.5 1280 O7 620 10 21.14 0.8 397.9 997 O8 665 10 16.38 0.8 364.9 883 O22 673.75 7.5 15.70 1 443.1 707 O9 681.25 7.5 15.11 0.8 350.3 745 O10 708.75 10 12.73 0.8 332.4 785 O11 753.75 7.5 10.33 1 377.7 605 O12 761.25 2.5 6.09 1 369.5 232 O13 764.375 3.75 7.13 1 373.4 305 O23 767.5 2.5 7.58 0.68 250.0 330 O14/15 778.75 15 9.18 0.8 277.5 812 O16/17 865 20 6.17 0.8 229.5 666 O18 885 10 6.00 1 281.0 395 O19 900 10 4.73 0.9 237.6 308 O20 940 20 2.39 0.7 171.7 203 O21 1020 40 3.86 0.8 163.7 152

OLCI (vs. Meris) Bands

MERIS heritage OLCI new bands

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26-Sep-2008

Chlorophyll Atlas of the North Sea (MERIS) Close heritage to MERIS (spectral bands

  • and radiometric performances)

Improvement of MERIS performances:

  • number of spectral bands (from 15 to 21)
  • Reduced sun glint by camera tilt in west

direction

  • Full Resolution (FR, 300m) also over

land/ocean,

  • Reduced Resolution (RR, 1200m) over

Ocean binned on ground (L1B)

  • improved stray light characterisation
  • improved coverage Ocean < 4 days,

Land < 3 days (MERIS eff. 15 days!)

  • Timeliness: 3 hours NRT Level 1 product
  • 100% overlap with SLSTR

=> improved L2 products (e.g., Cla, PFTs, HAB, Transparency, Sediment loading, Turbidity, NDVI, MGVI, MTCI, faPAR, LAI) Comparison MERIS-OLCI

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26-Sep-2008

SLSTR Objectives

  • Strong heritage from
  • A(A)TSR (spectral
  • channels and rad.
  • performances)
  • Continue high

precision IR SST series from A(A)TSR!

  • Land Surface
  • Temperatures
  • Surface albedo over
  • water/land
  • Synergy between OLCI and SLSTR (new products)
  • For Level 2 products, same or better performance as ENVISAT
  • Support of VEGETATION-type products (option)
  • IR channels adapted to support Fire Monitoring (option)

Sea and Land Surface Temperature Radiometer (SLSTR)

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26-Sep-2008

  • 2 observation views (dual view):

– Near-nadir view: FOV allowing a swath: ~1700km – Inclined view with an OZA of 55º, i.e., swath: ~750km

  • looking in backward direction
  • On ground resolution (SSD):

– 500 m (solar, 0.55-2.2μm) – 1000 m (TIR, 3.7/10.95/12μm)

  • Inter-channel spatial co-registration: < 0.1 SSD

SLSTR Swath Geometry

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Technical:

  • 7 AATSR & 2 additional bands
  • (1.375 , 2.2μm)
  • NEDT < 0.08K (TIR)
  • SNR = 20 (solar @ Lmin)
  • Absolute accuracy < 2-5%, 0.2K
  • Radiom. Stability < 0.1%, 0.08K
  • Polarisation sensitivity < 0.07

Compared to AATSR:

  • 3 instead of 1 mechanism
  • (2 scanners and one flip mechanism)
  • More complex front-end and electronics
  • New detector technology (multiple pixels)

SLSTR Overview

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26-Sep-2008

  • dual view, each having its own scanner (flat scan mirrors)
  • scan of 2 x Earth and calibration sources (BBs, VISCAL)
  • views are seen by the front collecting and refocusing optics (Primary Mirrors)
  • recombination optics to bring 2 optical paths into a single set of Focal Plane

Assemblies (FPA) after a common field plane used as intermediate field stop

  • FPA consists of a cryogenically cooled dewar, hosting the 6 (SW)IR and 3 VIS bands

Instrument Principle

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  • absolute rad. accuracy (S1-

S6) : <5% (EOL) <2% (BOL)

  • absolute rad. accuracy

(S7/8/9) : 0.2 K

  • polarisation sensitivity < 0.07

(S1-S6) or < 0.10 (S7/8/9)

  • stability (S1-S6): <0.1%
  • stability (S7/8/9): <0.08K

Band λcenter [μm] Δλ [μm] SNR [-] / NeΔT [mK] SSD [km] S1 0.555 0.02 20 0.5 S2 0.659 0.02 20 0.5 S3 0.865 0.02 20 0.5 S4 1.375 0.015 20 0.5 S5 1.61 0.06 20 0.5 S6 2.25 0.05 20 0.5 S7 3.74 0.38 80 mK 1.0 S8 10.95 0.9 80 mK 1.0 S9 12 1.0 80 mK 1.0 Band λcenter [μm] Δλ [μm] Tmax [K] SSD [km] F1 3.74 0.38 500 1.0 F2 10.95 0.9 400 1.0 Sea & Land Surface Bands Active Fire Bands final decision on F1 & F2 implementation after PDR SLSTR Performance

AATSR heritage SLSTR new bands

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26-Sep-2008

OLCI/SLSTR solar bands

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26-Sep-2008

Ground Processor Prototype

21 OLCI & 9 SLSTR as ISP,

  • incl. cal data & NAVATT on

camera/instrument grids 21 OLCI & 9 SLSTR as TOA radiance, incl. ortho- geolocated Lon-Lat values, sun/view angels, meteo, quality data 30 bands, co-registered Level 2 L2 Ocean/Land

  • rad. products

L2 VGT products L2 Ocean/Land

  • temp. products

SLST Level 1B product OLCI raw data OLCI Level 0 processing OLCI Level 0 product OLCI Level 1B processing OLCI Level 1B product SLST raw data SLST Level 0 processing SLST Level 0 product SLST Level 1B processing Optical Level 1C processing Vegetation Level 1C product

SERVICE MODULE

NAVATT packets

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Product Level 2

OLCI L1b SLST L1b Combined OLCI+SLST L1c OLCI L2 processing SLST L2 processing Land Vegetation products processing Water Products Land Products Sea Surface Temperature Land Surface Temperature Surface Directional Reflectances S3 Optical Level 1 Processor S-3 Optical Level 2 Processor Auxiliary Data Files

Partners: ARGANS consultant, UK ACRI-ST, France Brockmann Consult (BC), Germany ELSAG DATAMAT (DATAMAT), Italy Rutherford Appleton Laboratory (RAL), UK Experts: Chris Merchant, University of Edinburgh, UK David Antoine, LOV Fred Prata, Nilu, Norway Gerald Moore, Bio-optika, Jadunandan Dash, University of Southampton, John Remedios, University of Leicester, UK Jurgen Fischer, FUB, Germany, Martin Wooster, KCL, UK Nadine Gobron, JRC, Italy Peter North, University of Swansea, UK Richard Santer, LISE, France, Roger Saunders, UK Met Office, UK Roland Doerffer, GKSS, Germany

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Conclusion GMES Sentinel-3 is a series of operational satellites that will guarantee access to an uninterrupted flow of robust global data products. Together with the other Sentinels, this mission will fulfil the monitoring needs of the GMES marine and land services and climate research communities. The improved design of the optical payload and the respective data products will allow a data continuity the next decade to come. ` Next steps: OLCI PDR: 15-Oct-2008 (close out) Sat PDR: End Oct-2008 (close out) PDR of SLSTR: End-2008 Sat CDR: Apr-2010 Sat FAR: 2012

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  • ESA is currently developing 3 satellite systems forming part of the

Space Component of GMES programme (Global Monitoring for Environment and Security): – S1: C-band SAR, – S2: Multispectral optical imager, – S3: Wide-swath, low resolution VIS - IR spectro-radiometers and a radar altimeter package.

  • Each Sentinel mission has stringent revisit, coverage and mission

life cycle requirements (>15 years), which require the deployment of several satellites for each mission. GMES Sentinel-3 Mission Overview